This invention concerns methods and compositions for inhibiting fungus and mold growth of organic matter, particularly crops and animal feedstuffs.
Organic matter, particularly in a moist and warm environment, is highly susceptible to attack by fungi and molds. The problems of fungus and mold growth are particularly acute in the storage of crops, such as seeds and cereal grains. Several methods are or have been used to preserve such crops, e.g., grains, during storage. The most common method is to dry the grain to below about 15 percent by weight moisture and store it in substantially moisture-free containers. Other physical treatments, such as refrigeration and storage techniques, e.g., sealing the grain in oxygen-free containers, have been used or suggested in the past.
Additionally, there have been a variety of chemical treatments used or proposed for preserving high moisture grain Large numbers of compounds have been tested for such use. See Cereal Chem., 28, 196-207 (1951); Plant Physiol., 24:2 241-254 (1949); Can. J. Research, 16C, 241-247 (1938); Grain Science, 104, 463-464 (1948); Ind. Eng. Chem., 7, 709-712 (1915); Yearbook of Agriculture, U.S.D.A. 1950-51; and U.S. Pat. No. 2,584,972.
Chemical treatments are advantageous over drying in that they may be readily carried out by the farmer at the harvest location without a large equipment investment. In this respect many farmers presently transport their freshly harvested grain to large independently operated dryers. Additionally, the grain does not have to be remoistened for feeding purposes when chemical treatment is employed. Also, special containers do not have to be used and the preservation is effective after the grain is removed from storage. Since grain may be used primarily as an animal feed, it is desirable, if not imperative, that the chemical used to treat the grain not leave toxic or potentially toxic residues on the grain. Because of this many excellent agricultural fungicides -- while highly effective -- are not considered practical for grain storage. Consequently, the agricultural industry has looked mainly at relatively innocuous materials which leave no such residues. Currently, propionic acid is being promoted for this use. It is highly effective, relatively inexpensive, allegedly non-toxic and fairly easy to handle and apply. See "Studies on Feed Spoilage", L. R. Richardson and J. V. Halick, Texas Agr. Expt. Stat. Bull. 879 (1957) and British Pat. No. 1,155,485.